Mayor Thomas M. Menino is giving a 60-day extension to street vendors in Downtown Crossing after the pushcart operators fought back with a lawsuit and online petition to let them stay in business.

The complaint filed Monday against the City of Boston and the Downtown Boston Business Improvement District accuses officials of breaking promises to let the pushcarts operate through this year and seeks an injunction to prevent them from getting kicked out.

The suit comes days after the Downtown Crossing business group confirmed it would not continue the pushcart program after permits for the 27 vendors expire at the end of March.

“Shutting down the program will destroy my life,” said Julio Calderon, who filed the lawsuit and has operated several pushcarts in Downtown Crossing for over 20 years. “For me, this is the worst thing that could happen.”

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Calderon, who runs the Discovery Imports pushcart, said the business improvement district made clear he could continue operating through the end of 2013. As a result, Calderon said, he has incurred costs such as storage fees for the pushcarts and merchandise purchases in advance of the tourist season.

Rosemarie Sansone, president of the business improvement district — a group of property owners in the area — could not be reached for comment. In an interview Friday, Sansone said the association expects new and existing businesses will be able to apply to participate in an interim pushcart program this spring so the district can test different merchandise and locations.

She said consultants hired by the group are working on plans to launch a smaller and better pushcart program next year that could include new retailers such as food trucks.

But many vendors said they were not informed about the upcoming termination and are upset that they are being forced out after sticking by Downtown Crossing during lean times caused by the recession and the stalled Filene’s project, which left a massive crater in the middle of the neighborhood.

“They never told us anything about it,” said Driss Beramdane, who has sold sunglasses from his New Look cart for about 14 years. “I’m worried that as soon as we leave, they will bring in new merchants there and they will forget about us.”

Menino has also expressed opposition to efforts to end the program.

“The vendors who are in Downtown Crossing have been there in the bad times and never walked away — they should be allowed to stay, and we will help them stay to enjoy the good times, too. I believe it can and should, happen,” he said Monday.

Over the past year, the long-struggling Downtown Crossing area has become a major construction hub as developers build new residences and open trendy restaurants. The revitalization includes a huge tower that will be erected on the former Filene’s department store site.

Meanwhile, supporters of the pushcart program have launched an online petition at Change.org to save the vendors. As of late Monday, it had more than 600 signatures.

James DiSabatino, owner of Roxy’s Grilled Cheese Truck, used his Facebook page to encourage people to support the petition.

“Downtown Crossing wants to push street vendors out of Downtown Crossing, despite the fact that they’ve outlived most of the big businesses in the neighborhood over the years,” he wrote. “I’ve even heard that they want to bring food trucks there, but I’m not willing to cash in on another small business’s misfortune.”

Lynne Winchester, who works in the Downtown Crossing area, said the food carts and other street vendors have served the neighborhood well for years.

“They should be allowed to stay and upgrade if necessary, but this action seems drastic,” she said. “Until the gleaming tower is built and upgrades in place, why put people out of work who are providing a vital service to the area?”